Hydraulic impact device

ABSTRACT

An hydraulically powered impact device intended for rock drilling having a hydraulic fluid section for reciprocately powering an impact piston and a non-hydraulic section into which the impact piston as well as a drill stem adapter extend. The non-hydraulic section, which contains a flush medium supply chamber and a rotation transmitting chuck bushing, is connected to a pressure air source for establishing two separate pressure air barriers, the objects of which are to seal off, lubricate and cool the non-hydraulic section.

' United States Patent Ekwall et a1.

[ 1 Nov. 25, 1975 1 HYDRAULIC IMPACT DEVICE 3,028,771 4 1962 Bunnell 17357 3,774,700 11/1973 Shepherd 173/DlG. 3 [75] InventorscarlfliostaBernhard Elma", 3,797,584 3/1974 Bailey et a1. l73/D1G.3

salts obaden; Sven Ingemar Johansson SaItSjOBOO both of FOREIGN PATENTSOR APPLICATIONS Sweden 2,126,776 6/1972 France 173/D1G. 3 2,029,40412/1971 Germany 173/DIG. 3 [73] Assigneez Atlas Copco Aktlebolag, Nacka,

Sweden Primary Examiner-.lames A. Leppink [22] Filed: July 23, 1974Attorney, Agent, or FirmF1ynn & Frishauf [21] Appl. No.: 490,985 57ABSTRACT An hydraulically powered impact device intended for [30]Foreign Application Priority Data rock drilling having a hydraulic fluidsection for recip- Aug. 2, 1973 Sweden 7310634 rocately p ng n imp ctpiston and a nonhydraulic section into which the impact piston as well[52] U.S. Cl 173/57; l73/DIG. 3 as a drill stem p r x n The nn-hydraulic sec- [51] Int. Cl. E21C 7/00 tion, which contains a flush im pply ch mber [58] Field of Search 173/57,74, 80,61, 63 n a rotationtransmitting chuck ng. is

nected to a pressure air source for establishing two [56] References Citd separate pressure air barriers, the objects of which are UNITED STATESPATENTS to seal off, lubricate and cool'the non-hydraulic sec- 651,4876/1900 Leyner 173/63 892,082 6/1908 PrelIwitz 173/61 8 Claims, 1 DrawingFigure 01L 50 L 42 1151511110 a 23 DEVICE SOURCE 26 I7 46 I8 3 45 22 A1i///\ 437962 36 3O 37 4/ A 4O I2 US. Patent Nov. 25, 1975 HYDRAULICIMPACT DEVICE This invention relates to hydraulic impact devicesintended for rock drilling. More specifically, the invention relates tohydraulic impact devices provided with tool rotating as well as flushmedium supply means.

Previously known hydraulic impact devices are disadvantageous in thattheir reliability as regard operation is relatively low. One reason forthat is the fact that such impact devices are very sensitive for dustand similar strange particles which very easily cause choking up of thehydraulic system.

Another reason for operation disturbances is that the non-hydraulicsection of theimpact device, e.g. the

section, which is sealed off from hydraulic fluid, is exposed to hardwear and choking up 'because of poor sealing relative to the ambient.

A further problem concerning hydraulic impact devices is that the partswhich are provided with bearing surfaces, for instance the chuckbushing, and which are located in the non-hydraulic section areinsufficiently lubricated and cooled. As a consequence thereof, anunacceptable hard wear occurs resulting in too large clearances and agathering of wear products.

One object of the invention is to effectively prevent dust and similarparticles outside the machine as well as flush medium, from the flushmedium supply means from getting into contact with the hydraulic systemand other sensitive means of the machine.

Another object of the invention is to accomplish a desirable lubricationof the mechanical means, like tool rotating and recoil damping means,which are located within the non-hydraulic section of the device.

Still another object of the present invention is to accomplish coolingof the non-hydraulic section of the device as well as removing of wearproducts therefrom.

BRIEF DESCRIPTION OF THE DRAWINGS One embodiment of the invention ishereinafter described in detail with reference to the annexed drawing,which shows a longitudinal section through a separately rotated rockdrill having an impact device according to the invention. However, thehydraulic fluid section, intended for actuating the impact piston, isnot shown in detail because it is of a conventional type and does notconstitute a part of the invention.

DETAILED DESCRIPTION OF ILLUSTRATED EMBODIMENT The disclosed rock drillcomprises a housing 1 which includes an hydraulic fluid section 2 andnon-hydraulic section 3, e.g. the section which is sealed off fromhydraulic fluid. An impact piston 4 extends from the hydraulic fluidsection 2, wherein it is reciprocately powered, into the non-hydraulicsection 3. The two main sections of the housing 1 are separated by apacking device which surrounds the impact piston 4 and which comprises aclearance seal ring 6 and a couple of resilient packing rings 7. Betweenthe clearance seal ring 6 and the packing rings 7 there is a draincompartment 9 provided with outlet passages 8 through which hydraulicfluid which might leak across the clearance seal ring 6 is drained.

The non-hydraulic section 3 of the housing 1 accomodates the rear endpart of a drill stem adapter 11 which is provided with an axial flushmedium passage 10. For this purpose the housing is provided with a toolaperture 12 at its front end. Moreover, this section of the housing 1contains a chuck bushing 13 which surrounds the drill stem adapter 11.The chuck bushing is rigidly mounted in a socket wheel 14 which isrotatably powered by a motor 16 through a gear 15. The socket wheel 14is journalled in the housing 1 by means of two roller bearings l7, l8and is provided with an outer gear ring which forms a part of the gear15. For cooperation with the chuck bushing 13, the drill stem adapter isprovided with a widened portion 19 the outer contour of which is adaptedto that of the aperture in the chuck bushing 13.

Within the socket wheel 14, coaxially with the chuck bushing 13, thereis arranged an abutment sleeve 21 for transferring advance forcesapplied upon the housing to the drill stem adapter. This sleeve 21 isaxially displaceable relative to the socket wheel 14 which sleeve isbiased toward its forward-most position by means of a spring 22. In thisposition the abutment sleeve 21 abuts against the rear end of the chuckbushing 13. At its opposite end, the spring 22 rests against a thrustring 23 which is rotatably journalled within the housing 1 by means of aroller bearing 24 of the axial thrust type.

During drilling, the forward end of the abutment sleeve 21 is arrangedto rest against the widened portion 19 of the drill stem adapter 11 fortransferring advance forces acting upon the rock drill to the drill stemvia the spring 22 and the thrust ring 23. The spring 22 is intended toabsorb recoil impact from the drill stem and thereby protect the impactdevice from undesirable strains. The impact damping effect of the spring22 enables use of a roller bearing as axial thrust bearing 24.

The housing 1 is provided with two seal rings 26, 27 which are arrangedto cooperate with the outer periphery of the socket wheel 14 and whichenclose the bearings 19 and 18 and the gear 15. Thereby, this part ofthe housing is separated from the rest of the nonhydraulic section 3 ofthe housing 1. The bearings 19 and 18 and the gear 15 are lubricatedwith grease.

Further, the impact device comprises a flush medium block 28 situated infront of the chuck bushing 13 and intended for supplying flush medium,for instance water, to the flush medium passage 10 of the drill stemadapter 11. For this purpose, the flush medium block 28 contains a flushmedium chamber 29 which surrounds the drill stem adapter 11. An annulargroove 30 is formed on the outer peripheri of the flush medium block 28which groove communicates with the chamber 29. The annular groove 30also communicates with a flush medium supply conduit 32 through apassage 33 in the housing 1.

The flush medium chamber 29 is sealed off by means of two packing rings34, 35 cooperating with the adapter 1 1 whereas the annular groove 30 issealed off by means of two packing rings 36 and 37 cooperating with thehousing 1.

In the front part of the housing 1, between the flush medium block 28and the tool aperture 12, a support sleeve 40 is rotatably journalled inthe housing 1 by means of a bearing 41. The support sleeve 40 isarranged to form a radial support for the drill stem adapter 11 duringdrilling.

The non-hydraulic section 3 of the housing 1 is connected to a pressureair source through a conduit 42 and an inlet passage 43. The conduit 42is connected to a metering device 50 for adding lubricating oil to thepressure air. The inlet passage, 43 is connected to two inlet openings44 and 45 in the recoil damping part of the housing 1 and to a passage46 through which pressure air is conducted to the rear end of thesupport sleeve 40. The inlet opening 44 is located adjacent the axialthrust bearing 24 and the inlet opening 45 adjacent the abutment sleeve21.

The housing 1 is also provided with two pressure air outlets. One ofthese is constituted by an annular space formed between the housing 1and the adapter 11 within the tool aperture 12. The other air outlet isconstituted by a passage 48 which interconnects the atmosphere and adrain chamber 49. The latter is located in the rear part of the flushmedium block 28 and surrounds the drill stem 11 just in front of thechuck bushing 13.

This air passage arrangement enables establishing of two separatepressure air barriers the objects of which are to obtain a seal relativeto the ambient as, well as clean blowing, lubricating and cooling of thenonhydraulic section 3 of the housing 1.

The forward-most of the pressure air barriers is constituted by an airflow which extends from the passage 46 through the axial clearancebetween the support sleeve 40 and the flush medium block 28, and leavesthe housing through the support sleeve 40 and the tool aperture 12.Hereby, a forwardly directed, annular air flow is accomplished which airflow acts as a seal around the drill stern adapter 11 and preventseffectively dust and other strange particles from entering thehousing 1. By means of this air flow barrier there is also accomplishedlubrication and cooling of the support sleeve 40 and the bearing 41.

In order to obtain a more current air flow between the support sleeve 40and the flush medium block 28, the former may be provided with radiallydirected grooves at its rear end.

The rear pressure air barrier is constituted partly by an air flow andpartly by a pressure air volume. The latter is obtained in that the airflow which passes the inlet openings 44 and 45 is restricted whenpassing through the machine, whereby the part of the housing 1 whichissituated betwen the flush medium block 28 and the hydraluic seals 6and 7 is put under pressure. By means of this pressure air volumeparticles are prevented from travelling backwards through the machineand get into contact with the impact piston 4 and the seal rings 7.

This sealing effect is improved by a flow of pressure air passingthrough the outer and inner clearances of the abutment sleeve 21 andfurther through the inner clearance of the chuck bushing 13. This airflow leaves the housing through the drain chamber 49 and the passage 48,and accomplishes lubrication, cooling and clean blowing of all partslocated within the nonhydraulic section of the housing.

In order to obtain a more current air flow, the abutment sleeve 21 maybe provided with outer and may be also inner axial grooves and the chuckbushing 13 with inner axial grooves. The chuck bushing 13 may also beprovided with radial grooves at its rear end.

Two parts of the housing 1 are separated from the air flow, namely thegrease lubricated gear zone surrounding the socket wheel 14 and theflush medium zone constituted by the annular groove 30 and the flushmedium chamber 29. However, the latter is in itself a seal barrierbetween the tool aperture 12 and the hydraulic fluid seals 6 and 7,through which zone strange particles cannot pass. Yet, the flush mediumitself may ooze" out backwardly, which is a serious problem when wateris used as flushing medium. However, flush waterthat might ooze outcannot reach further backwards in the impact device than to the drainchamber 49 where the pressure air flow brings it out to the atmospherethrough the passage 48.

So, the rear pressure air barrier has a very important task inprotecting the impact device from leaking flush water. Other, at leastas important tasks are to lubricate and cool the different parts of theimpact device as well as to transport wear products out of the machine.

The invention is not limited to the shown and de scribed embodiment butcan be freely varied within the scope of the claims.

What we claim is:

1. A hydraulic impact device intended for rock drilling, comprising:

a housing and an impact piston, said housing being divided into ahydraulic fluid section in whichthe impact piston is reciprocatelypowered, and a nonhydraulic section into which the forward end of theimpact piston extends;

a tool aperture provided in the non-hydraulic section for receiving therear end of a drill stem or drill stem adapter;

a flush medium supply chamber provided in the nonhydraulic section incommunication with the tool aperture; and

pressure air supply means provided in the nonhydraulic section of thehousing and including means for coupling pressure air in front of andbehind the flush medium supply chamber establishing two pressure airbarriers in the non-hydraulic section, one in front of and one behindthe flush medium supply chamber relative to the impact direc-' tron.

2. Impact device according to claim 1 comprising a metering devicecoupling a pressure air source to said pressure air supply means, saidmetering device supply; ing lubricating oil to the pressure air.

3. Impact device according to claim 1 wherein said pressure air supplymeans comprises passage means in i ber and the hydraulic fluid section;and said pressure air supply means includes at least one pressure airinlet opening in the housing behind the chuck bushing and an air outletopening in the housing in front of the chuck bushing, relating to theimpact direction, the

chuck bushing permitting an air flow therethrough,

whereby the rear pressure air barrier is comprised of an air flowextending through said chuck bushing.

5. Impact device according to claim.4 comprising a metering devicecoupling a pressure air source to said pressure air supply means, saidmetering device supplying lubricating oil to the pressure air.

6. Impact device according to claim 1, comprising an annular spacecommunicating with the tool aperture and wherein said pressure airsupply means includes an air outlet opening in the housing in front ofthe chuck bushing, relating to the impact direction, the chuck bushingpermitting an air flow therethrough, whereby the rear pressure airbarrier is comprised of an air flow extending through said chuckbushing.

8. Impact device according to claim 6 comprising a metering devicecoupling a pressure air source to said pressure air supply means, saidmetering device supplying lubricating oil to the pressure air.

1. A hydraulic impact device intended for rock drilling, comprising: a housing and an impact piston, said housing being divided into a hydraulic fluid section in which the impact piston is reciprocately powered, and a non-hydraulic section into which the forward end of the impact piston extends; a tool aperture provided in the non-hydraulic section for receiving the rear end of a drill stem or drill stem adapter; a flush medium supply chamber provided in the non-hydraulic section in communication with the tool aperture; and pressure air supply means provided in the non-hydraulic section of the housing and including means for coupling pressure air in front of and behind the flush medium supply chamber establishing two pressure air barriers in the non-hydraulic section, one in front of and one behind the flush medium supply chamber relative to the impact direction.
 2. Impact device according to claim 1 comprising a metering device coupling a pressure air source to said pressure air supply means, said metering device supplying lubricating oil to the pressure air.
 3. Impact device according to claim 1 wherein said pressure air supply means comprises passage means in said non-hydraulic section of said housing, said passage means including a first passage extending in front of the flush medium supply chamber and at least one passage extending behind the flush medium supply chamber.
 4. Impact device according to claim 1 comprising a rotation transmitting chuck bushing mounted in said non-hydraulic section for cooperation with the rear end of a drill stem or drill stem adapter, the chuck bushing being located between the flush medium supply chamber and the hydraulic fluid section; and said pressure air supply means includes at least one pressure air inlet opening in the housing behind the chuck bushing and an air outlet opening in the housing in front of the chuck bushing, relating to the impact direction, the chuck bushing permitting an air flow therethrough, whereby the rear pressure air barrier is comprised of an air flow extending through said chuck bushing.
 5. Impact device according to claim 4 comprising a metering device coupling a pressure air source to said pressure air supply means, said metering device supplying lubricating oil to the pressure air.
 6. Impact device according to claim 1, comprising an annular space communicating with the tool aperture and wherein said pressure air supply means includes means for supplying pressure air to said annular space, the forward pressure air barrier being comprised of an air flow extending out through said annular space.
 7. Impact device according to claim 6 comprising a rotation transmitting chuck bushing mounted in said non-hydraulic section for cooperation with the rear end of a drill stem or drill stem adapter, the chuck bushing being located between the flush medium supply chamber and the hydraulic fluid section; and said pressure air supply means includes at least one pressure air inlet opening in the housing behind the chuck bushing and an air outlet opening in the housing in front of the chuck bushing, relating to the impact direction, the chuck bushing permitting an air flow therethrough, whereby the rear pressure air barrier is comprised of an air flow extending through said chuck bushing.
 8. Impact device according to claim 6 comprising a metering device coupling a pressure air source to said pressure air supply means, said metering device supplying lubricating oil to the pressure air. 